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In this paper, we present the investigation results of radiation-induced effects in metal-oxide-semiconductor (MOS) doped with moderate amounts of Zinc Oxide (ZnO) as a potential candidate for space-borne application. The samples were fabricated via the sputtering method at a working pressure of 3mTorr and a deposition temperature of 300oC. The ZnO samples were exposed to 1.25-MeV gamma-ray utilizing Co60 source, and their electronic response was measured at ionizing doses ranging from 10 kGy to 300 kGy. A comparative work was performed through finite element method to simulate the electronic response of the PN junction diode due to ionizing radiation. The results indicate that the ideality factor of the MOS diode increases as the ionizing dose increases, rendering it unsuitable for use as a diode. The degradation of the electrical parameters was also simulated, showing the increase in hole concentration. These findings suggest that the ejection of electrons occurred, which agrees with the gamma radiation effects trend. Furthermore, as the intensity of radiation increases, the spatial charge that arises from the separation of hole-electron pairs results in a substantial reduction of the electric field in the central portion of the n-type region. These findings provide insights into the degradation of electrical parameters in MOS devices under gamma radiation and have implications for their use in space-borne applications.

Photochemical ozone pollution is a serious air quality problem under weak synoptic conditions in many areas worldwide. Volatile organic compounds (VOCs) are largely responsible for ozone production in urban areas where NOx mixing ratios are high while usually not a limiting precursor to ozone. In this study, the Community Multiscale Air Quality model – Higher-order Direct Decoupled Method (CMAQ-HDDM) at an urban-scale resolution (1.0 km x 1.0 km) in conjunction with positive matrix factorization (PMF) was used to identify the dominant sources of highly sensitive VOC species to ozone formation in southern Taiwan, a complex region of coastal urban and industrial parks and inland mountainous areas. First-order, second-order and cross sensitivities of ozone concentrations to domain-wide (i.e. urban, suburban and rural) NOx and VOC emissions were determined for the study area. Negative (positive) first-order sensitivities to NOx emissions are dominant over urban (inland) areas, confirming ozone production sensitivity favors the VOC-limited regime (NOx-limited regime) in southern Taiwan. Furthermore, most of the urban areas also exhibited negative second-order sensitivity to NOx emissions, indicating a negative O3 convex response where the linear increase of O3 from decreasing NOx emissions was largely attenuated by the non-linear effects. Due to the solidly VOC-limited regime and the relative insensitivity of O3 production to increases or decreases of NOx emissions, this study pursued the VOC species that contributed the most to ozone formation. PMF analysis driven by VOCs resolved 8 factors including mixed industry (21 %), vehicle emissions (22 %), solvent usage (17 %), biogenic (12 %), plastic industry (10 %), aged air mass (7 %), motorcycle exhausts (7 %), and manufacturing industry (5 %). Furthermore, a composite index that quantitatively combined the CMAQ-HDDM sensitivity coefficient and PMF resolved factor contribution, was developed to identify the key VOC species that should be targeted for effective ozone abatement. Our results indicate that VOC control measures should target on (1) solvent usage for painting, coating and the printing industry, which emits abundant toluene and xylene, (2) gasoline fuel vehicle emissions of n-butane, isopentane, isobutane and n-pentane, and (3) ethylene and propylene emissions from the petrochemical industry.

PM10 (particulate matter with aerodynamic diameter below 10 microns) has always caught scientific attention due to its effect to human health. Predicting PM10 concentration is essential for early preventive measures, especially for cities such as Kota Kinabalu. Temporal data clustering may enhance accuracy of prediction model by group data in time range. However, the necessity of temporal data clustering has yet to be studied in Kota Kinabalu. OBJECTIVE. This research is conducted to compare significance of meteorological and pollutant factors for PM10 variation in clustered and unclustered data. METHODOLOGY. This study is focused in Kota Kinabalu, Sabah. The data for meteorological factors (Ws, Wd, Hum, Temp) and pollutant factors (CO2, NO2, O3, SO2, PM10) from 2003 to 2012 provided by Department of Environment are used for this research. Missing data are imputed using nearest neighbour method before it is clustered by monsoonal clustering. Unclustered and clustered datasets are analysed using principal component analysis (PCA) to check significance of factors contributing to PM10 concentration. FINDINGS. PCA results show that temporal clustering does not have noticeable effect on the variation of PM10 concentration. For all datasets, humidity and x-component wind speed have highest factor loading on PC1 and PC2 respectively. Further statistical analysis by 2-D regression shows that humidity (ρ = -0.60 ± 0.20) and temperature (ρ = 0.63 ± 0.11) have moderate to strong correlation towards PM10 concentration. This may be due to high humidity level and strong negative correlation between temperature and humidity (ρ = -0.91 ± 0.03). In contrast, both x- and y-component wind speed generally show weak correlation towards PM10, with ρ value of 0.09 ± 0.14 and 0.24 ± 0.18 respectively probably because of varying direction of particle dispersion. Fourier analysis further confirms this result by showing that human activity contributes major effect to variation of PM10 concentration.

A case of severe flash flood event affecting Kota Kinabalu (KK) on 17 Jul 2005 is analyzed by means of synoptic analysis using ERA-Interim Reanalysis and NCEP-FNL Data sets. In the synoptic scale, significant amount of precipitation was recorded in Sabah on 16 Jul and 17 Jul 2005. The heavy rainfall was associated to the upper-level ridge and lower-level cyclone observed over the South China Sea. Several low-pressure centers were also noticed over the Philippines Sea which were believed to intensify the heavy rainfall in Sabah. The vertical cross section for divergence along 116°E at Kota Kinabalu also revealed that a significant convergence was observed near the surface and accompanied by a strong updraft of divergence at upper-level. In the mesoscale, the ability of the convection-permitting WRF model to reproduce the convective cells associated with the heavy rainfall event is examined. A triply nested WRF model with the highest resolution of 5-km horizontal grid spacing was integrated with conventional analysis data. The simulation results were validated against observation from TRMM, CHIRPS, and PERSIANN-CDR. The modelled results agree moderately to the observation and fairly well simulated the initiation, intensification, and deceleration of heavy rainfall at nearly the right time except for some mismatch in terms of spatial distribution. The corresponding precipitation amount was also reasonably reproduced in its distribution but slightly overestimated. We also found that the cause of this severe flash flood is rooted to the prolonged heavy rainfall in the KK region induced by Typhoon Haitang.

Continental outflows from peninsular Southeast Asia and East Asia dominate the widespread dispersal of air pollutants over subtropical western North Pacific during spring and autumn, respectively. This study analyses the chemical composition and optical properties of PM

In the tropics, Langley calibration is often complicated by abundant cloud cover. The lack of an objective and robust cloud screening algorithm in Langley calibration is often problematic, especially for tropical climate sites where short, thin cirrus clouds are regular and abundant. Errors in this case could be misleading and undetectable unless one scrutinizes the performance of the best fitted line on the Langley regression individually. In this work, we introduce a new method to improve the sun photometer calibration past the Langley uncertainty over a tropical climate. A total of 20 Langley plots were collected using a portable spectrometer over a mid-altitude (1,574 m a.s.l.) tropical site at Kinabalu Park, Sabah. Data collected were daily added to Langley plots, and the characteristics of each Langley plot were carefully examined. Our results show that a gradual evolution pattern of the calculated Perez index in a time-series was observable for a good Langley plot, but days with poor Langley data basically demonstrated the opposite behavior. Taking advantage of this fact, the possibly contaminated data points were filtered by calculating the Perez derivative of each distinct air mass until a negative value was obtained. Any points that exhibited a negative derivative were considered bad data and discarded from the Langley regression. The implementation was completely automated and objective, rendering qualitative observation no longer necessary. The improved Langley plot exhibits significant improvement in addressing higher values for correlation, R, and lower values for aerosol optical depth, τa. The proposed method is sensitive enough to identify the occurrence of very short and thin cirrus clouds and is particularly useful for sun-photometer calibration over a tropical climate.

The application of optical based instrument in particulate matter monitoring has gained interest among researchers in recent years due to their high degree automation in providing real time reading of particulate matter concentrations. Such instrument usually comes in compact form making it compatible for in-situ monitoring especially for dense monitoring network. Theoretically, optical based instrument is unable to measure the mass concentration of particulate matter which is the key parameter in air quality monitoring. Instead, the mass concentration is calculated based on particle size distribution under assumptions that all particles is spherical using a known density. This being said, the accuracy of the reported mass concentration by optical instrument can be easily deteriorated if one of these assumptions is violated. Therefore, there is a need for a thorough evaluation on the particle to mass conversion factor in order to improve the accuracy of the reported mass concentrations by an optical instrument. In this study, the reported mass concentration from an optical based instrument as a function of particle distribution through random air sampling was investigated. The obtained data was then used to develop a parametric model for calculation of particulate mass concentration based on particle count distribution. The model developed was evaluated at several site and reported a good accuracy with high correlation (R2 > 0.97) in estimation of mass concentration.

The sompoton is one of famous traditional musical instruments in Sabah. This instrument consists of several parts with the vibrator being the most important one. In this paper, the vibrator is modeled as a clamped bar with a uniformly distributed mass. By means of this model, the fundamental frequency is analyzed with the use of an equivalent single degree of freedom system (SDOF) and exact analysis. The vibrator is made of aluminum in different sizes and is excited using a constant air jet to obtain its fundamental resonance frequency. The fundamental frequency obtained from the experimental measurement is compared with the theoretical values calculated based on the equivalent SDOF and exact analysis theories. It is found that the exact analysis gives a closer value to the experimental results as compared to the SDOF system. Although both the experimental and theoretical results exhibit the same trend, they are different in magnitude. To overcome the differences in both theories, a correction factor is added to account for the production errors.

Photosynthesis process in plants generates numerous sources of bioenergy. However, only a small fraction is readily exploited for electrical energy. The impact of environmental factors is one of the significant physiological influences on the electrical potential of the plants. Hence, we developed a data acquisition (DAQ) system for instantaneous monitoring of electrical potential in plants and Aloe vera was used as a plant sample. The static response characterization, capability index (P/T), and Pearson’s coefficient of correlation procedures were applied to assess the reliability of the obtained data. This developed system offers the capability of in situ monitoring and detecting gradual changes in the electrical potential of plants up to a correlational strength of greater than 0.7. Interpretation of the electrical signal mechanisms in the Aloe vera plant and the optimization of the electricity can be achieved through the application of this monitoring system. This system, therefore, can serve as a tool to measure and analyze the electrical signals in plants at different conditions.

As compared to other methods, measurement of aerosol optical depth (AOD) using sunphotometers offer several advantages. However, it suffers a drawback as calibration of the instrument required to be performed at high altitude due to temporal drifts in the atmospheric condition during the calibration. To solve this, a new Langley calibration algorithm has been designed for AOD measurement using spectroradiometer instrument. The key advantages of the proposed algorithm are its objectivity, computational efficiency and the ability to detect short intervals of cloud transits. It avoids travelling to high altitude mountain that the conventional calibration procedure always practiced for frequent calibration. Most importantly, neither it requires priori knowledge of the instrument calibration nor a collocated calibrated instrument for nominal calibration transfer to perform the cloud-screening procedure.

This chapter presents a detailed overview on the theory of aerosol optical depth retrieval with the emphasis on ground-based sunphotometry technique. To further discuss on the calibration issue as mentioned previously, this overview also includes the principle of the oldest passive ground-based calibration method, Langley calibration to provide an insight on the working mechanism of the method. The final part in this chapter compiles the previous existing Langley calibration method in a chronological sequence to render a better comprehension on its development from the past to present time.

To avoid the unnecessary needs to travel to high altitude for sunphotometers calibration, Perez-Dumotier calibration algorithm has been used as an objective means to select the right intensity data so that the calibration can be performed at any altitude levels. The governing theory of the algorithm was discussed in the previous chapter. This chapter presents information on how to implement the Perez-Dumotier calibration algorithm using actual field measurement. The implementation of the filtration procedure in step-by-step is discussed to render better framework of the proposed calibration algorithm. The aerosol retrieval inversion uses the extraterrestrial constant obtained from the final Langley plot to calculate retrieved AOD. The implementation example uses irradiance-matched technique by i-SMARTS radiative transfer code to derive corresponding reference AOD for validation purposes. The reliability of the technique was substantiated by radiative closure experiment to verify the promising direct solar irradiance to accurately derive the reference AOD values.

Aerosols are small particles suspended in air that have wide varying spatial and temporal distributions. The concentration of aerosol in total columnar atmosphere is normally measured using aerosol optical depth (AOD). In long-term monitoring stations, accurate AOD retrieval is often difficult due to the lack of frequent calibration. To overcome this problem, a near-sea-level Langley calibration algorithm is developed using the combination of clear-sky detection model and statistical filter. It attempts to produce a dataset that consists of only homogenous and stable atmospheric condition for the Langley calibration purposes. In this paper, a radiance-based validation method is performed to further investigate the feasibility and consistency of the proposed algorithm at different location, day, and time. The algorithm is validated using SMARTS model based n DNI value. The overall results confirmed that the proposed calibration algorithm feasible and consistent for measurements taken at different sites and weather conditions., {"references":["","P. W. Kiedron, J. J. Michalsky, J. L. Berndt, and L. C. Harrison, \"Comparison of spectral irradiance standards used to calibrate shortwave radiometers and spectroradiometers,\" Applied Optics, vol. 38, no. 2, pp. 2432–2439, 1999.","J. Slusser, J. Gibson, B. David, D. Kolinski, P. Disterhoft, K. Lantz, and A. Beaubien, \"Langley method for calibrating UV filter radiometer,\" Journal of Geophysical Research, vol. 105, no. D4, pp. 4841–49, 2000.","G. E. Shaw, \"Sunphotometry,\" Bulletin of the American Meteorological Society, vol. 64, no. 1, pp. 4–10, 1983.","T. M. Saeed and H. Al-Dashti, \"Optical and physical characterization of 'Iraqi freedom' dust storm, a case study,\" Theoretical and Applied Climatology, vol. 104, no. 1–2, pp. 123–137, Sep. 2010.","B. N. Holben, T. F. Eck, I. Slutske, D. Tanre, J. P. Buis, A. Setzer, E. Vermote, J. A. Reagan, Y. J. Kaufman, T. Nakajima, F. Lavenu, I. Jankowiak, and A. Smirnov, \"AERONET-A Federated Instrument Network and Data Archive for Aerosol Characterization,\" Remote Sensing of Environment, vol. 66, pp. 1–16, 1998.","J. H. W. Chang, J. Dayou, and J. Sentian, \"Development of near-sea-level calibration algorithm for aerosol optical depth measurement using ground-based spectrometer,\" To appear in Aerosol and Air Quality Research, 2013.","H. Djamila, C. C. Ming, and S. Kumaresan, \"Estimation of exterior vertical daylight for the humid tropic of Kota Kinabalu city in East Malaysia,\" Renewable Energy, vol. 36, no. 1, pp. 9–15, Jan. 2011.","A. Zain-Ahmed, K. Sopian, Z. Z. Abidin, and M. Y. H. Othman, \"The availability of daylight from tropical skies — a case study of Malaysia,\" Renewable Energy, vol. 25, pp. 21–30, 2002.","L. Harrison and J. Michalsky, \"Objective algorithms for the retrieval of optical depths from ground-based measurements.\" Applied optics, vol. 33, no. 22, pp. 5126–32, Aug. 1994.\n[10] J. H. W. Chang, J. Dayou, and J. Sentian, \"Diurnal Evolution of Solar Radiation in UV , PAR and NIR Bands in High Air Masses,\" Nature, Environment and Pollution Technology, vol. 12, no. 1, pp. 1–6, 2013.\n[11] J. H. W. Chang, J. Dayou, and J. Sentian, \"Investigation of Short Time Scale Variation of Solar Radiation Spectrum in UV , PAR , and NIR Bands due to Atmospheric Aerosol and Water Vapor,\" World Academy of Science, Engineering and Technology, vol. 73, pp. 1112–1117, 2013.\n[12] C. A. Gueymard, \"Prediction and validation of cloudless shortwave solar spectra incident on horizontal, tilted, or tracking surfaces,\" Solar Energy, vol. 82, pp. 260–271, 2008.\n[13] D. G. Kaskaoutis and H. D. Kambezidis, “The role of aerosol models of the SMARTS code in predicting the spectral direct-beam irradiance in an urban area,” Renewable Energy, vol. 33, pp. 1532–1543, 2008."]}